Olefin oligomerization

ABSTRACT

This invention is to a method of oligomerizing an olefin feed stream. The olefin feed stream contains at least one C 2  to C 12  olefin to obtain an olefin feed stream and has less than 1,000 ppm by weight oxygenated hydrocarbon. The olefin is oligomerized by contacting with an acid based oligomerization catalyst.

This application claims priority to U.S. Provisional Patent ApplicationNo. 60/265,700, filed Feb. 1, 2002.

FIELD OF THE INVENTION

This invention relates to a process for oligomerizing olefin. Inparticular, this invention relates to a process for oligomerizing anolefin stream containing a low concentration of oxygenated hydrocarboncontaminants.

BACKGROUND OF THE INVENTION

The oligomerization of olefin compounds is conventionally accomplishedby catalytic reaction. Oligomerization catalysts are typically nickelbased catalysts or acid based catalysts. Generally, oligomerizationprocesses which use nickel based catalysts are carried out by forming ahomogenous suspension of catalyst, olefin feed and product, whereas theacid based catalyst systems are carried out using a flow-through, fixedbed type of arrangement. The homogeneous suspension type of system isgenerally much more technically difficult to operate, but offers certainadvantages in its ability to product a greater degree of “semi-linear”oligomer products. These semi-linear products are products with limitedbranches, and can be beneficial in certain uses such as further reactionto form plasticizers, solvents or diesel type fuels in which limitedbranching is desirable.

Cosyns, J. et al., in “Process for upgrading C₃, C₄ and C₅ olefinicstreams,” Pet. & Coal, Vol. 37, No. 4 (1995), describe a nickel basedcatalyst system known as the Dimersol® process. This process is usefulfor dimerizing or oligomerizing a variety of olefin feeds. Inparticular, the process is useful for dimerizing or oligomerizingpropylene, butylene and pentylene streams.

U.S. Pat. No. 6,143,942, to Verrelst et al., describes theoligomerization of C₂ to C₁₂ olefins using a mixture of ZSM-5 andZSM-22, and ZSM-57 and ZSM-22. The particular combination of catalystsproduces a high yield of trimer products.

U.S. Pat. No. 5,874,661, to Verrelst et al., describes a system forreducing branching of oligomerized olefins. In this system, lowerolefins, such as propene or butene, are oligomerized to an oligomer orhigher olefin using an acid based catalyst such as ZSM-5. The higherolefin is then isomerized also using an acid based catalyst, such asZSM-5 or ZSM-22, to isomerize the higher olefin and reduce the degree ofbranching. The isomerized higher olefin is then hydroformylated to formsurfactants and polyolefin stabilizers.

U.S. Pat. No. 5,762,800, to Mathys et al., describes a process foroligomerizing C₂ to C₁₂ alkenes using a zeolite oligomerizationcatalyst. The catalytic life of the catalyst is increased by hydratingthe olefin feed to the oligomerization reactor.

U.S. Pat. No. 6,049,017, to Vora et al., describes the dimerization of apredominantly n-butylene containing feed stream. The n-butylene feedstream is ultimately derived from an olefin stream containing a varietyof butylenes produced by a methanol to olefins reaction unit. Thebutylene stream from the methanol to olefins unit is pretreated by acombination of partial hydrogenation of dienes and isobutylene removalby way of an MTBE process, before sending the resulting n-butylenestream to the dimerization unit.

Often, efficiency of the oligomerization process is reduced due to thepresence of greater than desirable quantities of inert components in thefeed stream; for example, alkanes such as propane and butane. Theseinert components, in essence, take a free ride through the reactionsystem, taking up valuable reactor volume without being reacted todesirable products. Therefore, multiple separations processes to removeinert components are often required.

Olefin feed streams can also contain contaminants that act as poisons tooligomerization catalysts. For example, nickel based oligomerizationcatalysts are quite sensitive to sulfur and nitrogen. Such contaminantscan have a particularly significant impact on the active life of thecatalyst, shortening the life of the catalyst to the point where thereaction process is not feasible to operate.

It is, therefore, desirable to provide olefin feed streams which can beoligomerized at high efficiency and run for an extended period withoutcausing early replacement or regeneration of catalyst. It would beparticularly desirable to take advantage of an olefin feed stream whichneeds little pretreatment for use in an oligomerization system.

SUMMARY OF THE INVENTION

This invention provides a method for oligomerizing an olefin feedwithout substantially adversely affecting catalyst life. The oligomerproduct can be obtained without having to treat the olefin feed toremove contaminants such as sulfur and nitrogen. The oligomer product isoptionally converted to a hydroformylated product with desirablebranching characteristics.

In one embodiment, the invention provides a method of oligomerizingolefin which comprises removing oxygenated hydrocarbon from an olefinstream containing at least one C₂ to C₁₂ olefin to obtain an olefin feedstream comprising less than 1,000 ppm by weight oxygenated hydrocarbon.The olefin feed is contacted with an acid based oligomerization catalystto oligomerize the olefin in the olefin feed.

In another embodiment, the invention comprises contacting an oxygenatewith a molecular sieve catalyst to form an olefin stream containing atleast one C₂ to C₁₂ olefin. Oxygenated hydrocarbons showing up in theformed olefin stream are removed from the olefin stream to obtain anolefin feed stream comprising less than 1,000 ppm by weight oxygenatedhydrocarbon. The olefin feed stream is then contacted with an acid basedoligomerization catalyst to form an olefin oligomer.

An alternative embodiment comprises contacting the oxygenate with amolecular sieve catalyst to form an olefin stream containing at leastone C₂ to C₁₂ olefin. The a C₃ to C₆ olefin stream is recovered from theolefin stream, and oxygenated hydrocarbon is removed from the olefinstream to obtain an olefin feed stream comprising less than 1,000 ppm byweight oxygenated hydrocarbon. The olefin feed stream is then contactedwith an acid based oligomerization catalyst to form an olefin oligomer.

In another embodiment of the invention an olefin feed stream is providedwhich comprises at least one C₂ to C₁₂ olefin and oxygenatedhydrocarbon. Preferably, the oxygenated hydrocarbon is provided in theolefin stream at a concentration of greater than 5 ppm by weight andless than 1,000 ppm by weight. The provided olefin stream is thencontacted with a zeolite oligomerization catalyst to oligomerize theolefin in the olefin feed.

In yet another embodiment of the invention, the acid basedoligomerization catalyst is a zeolite oligomerization catalyst. Thezeolite oligomerization catalyst is desirably selected from the groupconsisting of TON, MTT, MFI, MEL, MTW, EUO, ZSM-57, ferrierites,offretites, ZSM-4, ZSM-18, Zeolite Beta, faujasites, zeolite L,mordenites, erionites and chabazites. Preferably, the zeoliteoligomerization catalyst is ZSM-22, ZSM-23 or ZSM-57, more preferablythe zeolite oligomerization catalyst is ZSM-22 or ZSM-23. The acid basedoligomerization catalyst can also be a solid phosphoric acid catalyst.

Surface activated zeolites such as mono-dimensional 10-ring zeolites,such as ZSM-22 or ZSM-23, are also useful as oligomerization catalysts.Such selectivated catalysts produce near linear oligomers.

It is desirable to have a reasonable quantity of olefin in the olefinfeed stream for better efficiency. Preferably, the olefin feed containsless than 50 wt % alkane; more preferably, the olefin feed contains atleast 50 wt % olefin.

In another embodiment of the invention, catalyst life is prolonged byhydrating the olefin feed prior to contacting with the oligomerizationcatalyst, particularly a zeolite oligomerization catalyst. Preferably,the hydrated olefin feed has a water content of 0.05 to 2 weightpercent.

BRIEF DESCRIPTION OF THE DRAWING

Examples of various embodiments of the invention are shown in theattached FIGURE which depicts data derived from the Examples.

DETAILED DESCRIPTION OF THE INVENTION

This invention provides a method of oligomerizing olefin by contactingan olefin feed with an acid based oligomerization catalyst. Examples ofan acid based oligomerization catalyst include solid phosphoric acidcatalysts and zeolite oligomeriation catalysts.

The solid phosphoric acid catalysts used in this invention can be anyconventional solid phosphoric acid catalyst that is active in olefinoligomerization reactions. Such catalysts comprise phosphoric acid on asilicon based support. Examples include phosphoric acid on silica gel,diatomaceous earth, and kieselguhr. More specific examples are found inU.S. Pat. Nos. 2,586,852; 2,713,560; and 4,675,463, the descriptions ofwhich are incorporated herein by reference.

The zeolite oligomerization catalysts can be any catalyst that is activein olefin oligomerization reactions. Such catalysts include, forexample, zeolites of the TON structure type (for example, ZSM-22, ISI-1,Theta-1, Nu-10, KZ-2); zeolites of the MTT structure type (for example,ZSM-23, KZ-1); zeolites of the MFI structure type (for example, ZSM-5);zeolites of the MEL structure type (for example, ZSM-11); zeolites ofthe MTW structure type (for example, ZSM-12); zeolites with the EUOstructure type (for example, EU-1); zeolite ZSM-57, or any member of theferrierite structure family. Other examples of suitable catalysts areoffretites, ZSM-4, ZSM-18 or zeolite beta. Synthesis of these catalystsare described in Synthesis of High-Silica Aluminosilicate Zeolites by P.A. Jacobs and J. A. Martens (published as volume 33 in the seriesStudies in Surface Science and Catalysis), the disclosure of which isincorporated herein by reference.

Additionally, the catalyst used in this invention can be a zeolitesynthesized without addition of a template. Examples include faujasites,zeolite L, mordenites, erionites and chabazites, the structures of whichare described in the Atlas of Zeolite Structure Types by W. M. Meier andD. H. Olson (published by Butterworths on behalf of the StructureCommission of the International Zeolite Association). Zeolite catalystshaving crystal structures that are essentially the same as the crystalstructures of the above-mentioned zeolite catalysts, but differ slightlytherefrom in chemical composition, can also be used. Examples of suchzeolites include zeolite catalysts obtained by removal of a number ofaluminum ions from, or by steaming of, the above-mentioned zeolitecatalysts, or zeolite catalysts obtained by addition of differentelements, for example, by impregnation or cation exchange or byincorporation during the zeolite synthesis (for example boron, iron andgallium).

Zeolite oligomerization catalysts can be made by any suitable method.One conventional technique includes heating a reaction mixturecontaining a source of silicon oxide, a source of aluminum oxide and, ifappropriate, an organic promoter, for example, a nitrogen orphosphorus-containing organic base, together optionally with an alkalimetal base, and separating the porous aluminosilicate crystals (zeoliteprecursor crystals) formed. The precursor crystals are then calcined inair or oxygen at a temperature exceeding 500° C.; for example, at atemperature of 550° C. for about 10 to about 20 hours. In oneembodiment, the calcined material is exchanged with ammonium ions (NH₄+)and subjected to conditions under which the ammonium ions decompose,with the formation of ammonia and a proton, thus producing an acidicform of the zeolite. Alternatively, the acidic form can be obtained byacid exchange with hydrochloric acid. If desired, however, the calcinedmaterial can be used as a catalyst without first being exchanged withammonium ions, since the material then already possesses acidic sites.The activity of the material is then significantly lower than that of amaterial that has been exchanged with ammonium ions and then subjectedto conditions under which the ammonium ions decompose.

Ammonium exchanged and calcined monodimensional 10-rings zeolites,examples of which include ZSM-22 and ZSM-23, can be treated toselectivate their surface, thereby forming a selectivated catlayst. Thisselectivation can be achieved in numerous ways. As one example, thezeolites can be titrated with an organic nitrogen base, such ascollidine. See, for example, U.S. Pat. No. 5,026,933 to Blain et al.,the description of which is incorporated herein by reference. Anotherexample is by depositing a crystalline Si:Al layer on a core of zeolite,such as ZSM-22 or ZSM-23, where this layer has a higher Si:Al ratio thanthe untreated zeolite. See, for example, U.S. Pat. No. 6,013,851, thedescription of which is incorporated herein by reference.

The olefin feed stream that is to be oligomerized in this inventionincludes at least one C₂ to C₁₂ olefin. Preferably the olefin feedstream comprises at least one C₂ to C₈ olefin, more preferably at leastone C₃ to C₆ olefin.

In one embodiment, the olefin feed steam that is oligomerized containsat least 50 wt % olefin. Preferably, the olefin feed stream comprises atleast about 55 wt % olefin, more preferably at least about 60 wt %olefin.

In another embodiment, the olefin feed stream comprises less than about50 wt % paraffin. More preferably, the olefin feed stream comprises lessthan about 45 wt % paraffin, more preferably less than about 40 wt %paraffin.

The inventors have found that the acid based oligomerization catalystsused in this invention are adversely sensitive to even low levels ofoxygenated hydrocarbons in the olefin feed. This sensitivity isdemonstrated by a significant reduction in catalyst life in the presenceof certain levels of oxygenated hydrocarbons. The exhibited sensitivityis quite unexpected, since it is known that addition of low levels ofwater (a non-hydrocarbon oxygenate) to the olefin feed can actuallyincrease the catalytic life of the zeolite oligomerization catalysts.See, for example, U.S. Pat. No. 5,672,800 which shows hydration canimprove zeolite oligomerization catalyst life.

Examples of oxygenated hydrocarbon to which the acid basedoligomerization catalysts are adversely sensitive are alcohols,aldehydes, ketones, ethers and carboxylic acids. Oxygenated hydrocarbonswhich particularly affect the acid based oligomerization catalystsinclude methanol, butyl alcohol, dimethyl ether, methyl ethyl ketone,acetic acid, and propionic acid.

In one embodiment of the invention, the olefin feed stream that is to beoligomerized comprises less than 1,000 ppm by weight of the oxygenatedhydrocarbon. Preferably, the olefin feed stream that is to beoligomerized comprises less than about 900 ppm by weight of theoxygenated hydrocarbon, more preferably less than about 800 ppm byweight of the oxygenated hydrocarbon.

It is not necessary that the olefin feed stream be completely devoid ofoxygenated hydrocarbon. An amount of oxygenated hydrocarbon can bepresent, so long as it does not significantly adversely affect catalyticlife of the oligomerization catalyst. In this regard, an olefin feedstream containing greater than about 500 ppm by weight oxygenatedhydrocarbon is tolerable. Preferably, the level is somewhat lower. Alower limit of greater than about 100 ppm by weight is more desirable,with a lower limit of at least about 50 ppm by weight being even moredesirable, and a lower limit of at least about 5 ppm by weight beingparticularly preferred. Lower limits of oxygenated hydrocarbon are notwarranted as the oligomerization catalyst can satisfactorily toleratevery low levels, and it is technically difficult to remove oxygenatedhydrocarbons to lower levels; particularly when the olefin feed streamis derived from processes such as oxygenate to olefins processes, whichwill generally contain substantial quantities of oxygenated hydrocarbonsin the olefin product.

In another embodiment of the invention, the olefin feed stream that isoligomerized in this invention is predominantly derived from anoxygenate to olefins unit; meaning that at least 50 wt % of the olefinfeed, preferably at least 60 wt %, and more preferably at least 70 wt %of the olefin feed, is derived from an oxygenate to olefins unit. Such afeed stream should be low in sulfur, nitrogen and chlorine, to theextent that essentially no pretreatment will be required for removal ofsuch components. In addition, such a feed stream should have arelatively low concentration of paraffins, compared to such sources asolefins from cracked hydrocarbon source. However, such a feed streamwill generally contain oxygenated hydrocarbon at a level which wouldlikely adversely impact catalytic life of the zeolite oligomerizationcatalyst. Therefore, removal of such components are likely required. Thebenefit in using an oxygenate to olefins stream is that lower levels ofinert components, such as propane and butane, are present.

Desirably, the olefin feed stream is obtained by contacting oxygenatewith a molecular sieve catalyst. The oxygenate comprises at least oneorganic compound which contains at least one oxygen atom, such asaliphatic alcohols, ethers, carbonyl compounds (aldehydes, ketones,carboxylic acids, carbonates, esters and the like). When the oxygenateis an alcohol, the alcohol includes an aliphatic moiety having from 1 to10 carbon atoms, more preferably from 1 to 4 carbon atoms.Representative alcohols include but are not necessarily limited to lowerstraight and branched chain aliphatic alcohols and their unsaturatedcounterparts. Examples of suitable oxygenate compounds include, but arenot limited to: methanol; ethanol; n-propanol; isopropanol; C₄-C₂₀alcohols; methyl ethyl ether; dimethyl ether; diethyl ether;di-isopropyl ether; formaldehyde; dimethyl carbonate; dimethyl ketone;acetic acid; and mixtures thereof. Preferred oxygenate compounds aremethanol, dimethyl ether, or a mixture thereof.

A molecular sieve catalyst is used in this invention in the oxygenate toolefin reaction. Such a molecular sieve is defined as any molecularsieve capable of converting an oxygenate to an olefin compound. Examplesof these molecular sieves include zeolites as well as non-zeolites, andare of the large, medium or small pore type. Small pore molecular sievesare preferred in one embodiment of this invention, however. As definedherein, small pore molecular sieves have a pore size of less than about5.0 Angstroms. Generally, suitable catalysts have a pore size rangingfrom about 3.5 to about 5.0 angstroms, preferably from about 4.0 toabout 5.0 Angstroms, and most preferably from about 4.3 to about 5.0Angstroms.

Zeolites which are particularly useful as an oxygenate to olefinscatalyst include the ZSM type zeolites. Examples of the ZSM typezeolites include ZSM-4, ZSM-5, ZSM-11, ZSM-12, ZSM-13, ZSM-22, ZSM-23,and ZSM-57.

Another type of olefin forming catalyst useful in this invention is onecontaining a silicoaluminophosphate (SAPO) molecular sieve.Silicoaluminophosphate molecular sieves are generally classified asbeing microporous materials having 8, 10, or 12 membered ringstructures. These ring structures can have an average pore size rangingfrom about 3.5 to about 15 angstroms. Preferred are the small pore SAPOmolecular sieves having an average pore size of less than about 5angstroms, preferably an average pore size ranging from about 3.5 toabout 5 angstroms, more preferably from about 3.5 to about 4.2angstroms. These pore sizes are typical of molecular sieves having 8membered rings.

According to one embodiment, substituted SAPOs can also be used inoxygenate to olefin reaction processes. These compounds are generallyknown as MeAPSOs or metal-containing silicoaluminophosphates. The metalcan be alkali metal ions (Group IA), alkaline earth metal ions (GroupIIA), rare earth ions (Group IIIB, including the lanthanoid elements:lanthanum, cerium, praseodymium, neodymium, samarium, europium,gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium andlutetium; and scandium or yttrium) and the additional transition cationsof Groups IVB, VB, VIB, VIIB, VIIIB, and IB.

Preferably, the Me represents atoms such as Zn, Mg, Mn, Co, Ni, Ga, Fe,Ti, Zr, Ge, Sn, and Cr. These atoms can be inserted into the tetrahedralframework through a [MeO₂] tetrahedral unit. The [MeO₂] tetrahedral unitcarries a net electric charge depending on the valence state of themetal substituent. When the metal component has a valence state of +2,+3, +4, +5, or +6, the net electric charge is between −2 and +2.Incorporation of the metal component is typically accomplished addingthe metal component during synthesis of the molecular sieve. However,post-synthesis ion exchange can also be used. In post synthesisexchange, the metal component will introduce cations into ion-exchangepositions at an open surface of the molecular sieve, not into theframework itself.

Suitable silicoaluminophosphate molecular sieves include SAPO-5, SAPO-8,SAPO-11, SAPO-16, SAPO-17, SAPO-18, SAPO-20, SAPO-31, SAPO-34, SAPO-35,SAPO-36, SAPO-37, SAPO-40, SAPO-41, SAPO-42, SAPO-44, SAPO-47, SAPO-56,the metal containing forms thereof, and mixtures thereof. Preferred areSAPO-18, SAPO-34, SAPO-35, SAPO-44, and SAPO-47, particularly SAPO-18and SAPO-34, including the metal containing forms thereof, and mixturesthereof. As used herein, the term mixture is synonymous with combinationand is considered a composition of matter having two or more componentsin varying proportions, regardless of their physical state.

An aluminophosphate (ALPO) molecular sieve can also be included in theoxygenate to olefins catalyst composition. Aluminophosphate molecularsieves are crystalline microporous oxides which can have an AIPO₄framework. They can have additional elements within the framework,typically have uniform pore dimensions ranging from about 3 angstroms toabout 10 angstroms, and are capable of making size selective separationsof molecular species. More than two dozen structure types have beenreported, including zeolite topological analogues. A more detaileddescription of the background and synthesis of aluminophosphates isfound in U.S. Pat. No. 4,310,440, which is incorporated herein byreference in its entirety. Preferred ALPO structures are ALPO-5,ALPO-11, ALPO-18, ALPO-31, ALPO-34, ALPO-36, ALPO-37, and ALPO-46. TheALPOs can also include a metal substituent in its framework. Preferably,the metal is selected from the group consisting of magnesium, manganese,zinc, cobalt, and mixtures thereof. These materials preferably exhibitadsorption, ionexchange and/or catalytic properties similar toaluminosilicate, aluminophosphate and silica aluminophosphate molecularsieve compositions. Members of this class and their preparation aredescribed in U.S. Pat. No. 4,567,029, incorporated herein by referencein its entirety.

The metal containing ALPOs have a three-dimensional microporous crystalframework structure of MO₂, AlO₂ and PO₂ tetrahedral units. These asmanufactured structures (which contain template prior to calcination)can be represented by empirical chemical composition, on an anhydrousbasis, as:mR: (M_(x)Al_(y)P_(z))O₂wherein “R” represents at least one organic templating agent present inthe intracrystalline pore system; “m” represents the moles of “R”present per mole of (M_(x)Al_(y)P_(z))O₂ and has a value of from zero to0.3, the maximum value in each case depending upon the moleculardimensions of the templating agent and the available void volume of thepore system of the particular metal aluminophosphate involved, “x”, “y”,and “z” represent the mole fractions of the metal “M”, (i.e. magnesium,manganese, zinc and cobalt), aluminum and phosphorus, respectively,present as tetrahedral oxides.

The metal containing ALPOs are sometimes referred to by the acronym asMeAPO. Also in those cases where the metal “Me” in the composition ismagnesium, the acronym MAPO is applied to the composition. SimilarlyZAPO, MnAPO and CoAPO are applied to the compositions which containzinc, manganese and cobalt respectively. To identify the variousstructural species which make up each of the subgeneric classes MAPO,ZAPO, CoAPO and MnAPO, each species is assigned a number and isidentified, for example, as ZAPO-5, MAPO-1 1, CoAPO-34 and so forth.

The silicoaluminophosphate molecular sieve is typically admixed (i.e.,blended) with other materials. When blended, the resulting compositionis typically referred to as a SAPO catalyst, with the catalystcomprising the SAPO molecular sieve.

Materials which can be blended with the molecular sieve can be variousinert or catalytically active materials, or various binder materials.These materials include compositions such as kaolin and other clays,various forms of rare earth metals, metal oxides, other non-zeolitecatalyst components, zeolite catalyst components, alumina or aluminasol, titania, zirconia, magnesia, thoria, beryllia, quartz, silica orsilica or silica sol, and mixtures thereof. These components are alsoeffective in reducing, inter alia, overall catalyst cost, acting as athermal sink to assist in heat shielding the catalyst duringregeneration, densifying the catalyst and increasing catalyst strength.It is particularly desirable that the inert materials that are used inthe catalyst to act as a thermal sink have a heat capacity of from about0.05 to about 1 cal/g-° C., more preferably from about 0.1 to about 0.8cal/g-° C., most preferably from about 0.1 to about 0.5 cal/g-° C.

Additional molecular sieve materials can be included as a part of theSAPO catalyst composition or they can be used as separate molecularsieve catalysts in admixture with the SAPO catalyst if desired.Structural types of small pore molecular sieves that are suitable foruse in this invention include AEI, AFT, APC, ATN, ATT, ATV, AWW, BIK,CAS, CHA, CHI, DAC, DDR, EDI, ERI, GOO, KFI, LEV, LOV, LTA, MON, PAU,PHI, RHO, ROG, THO, and substituted forms thereof. Structural types ofmedium pore molecular sieves that are suitable for use in this inventioninclude MFI, MEL, MTW, EUO, MTT, HEU, FER, AFO, AEL, TON, andsubstituted forms thereof. These small and medium pore molecular sievesare described in greater detail in the Atlas of Zeolite StructuralTypes, W. M. Meier and D. H. Olsen, Butterworth Heineman, 3rd ed., 1997,the detailed description of which is explicitly incorporated herein byreference. Preferred molecular sieves which can be combined with asilicoaluminophosphate catalyst include ZSM-5, ZSM-34, erionite, andchabazite.

The catalyst composition, according to an embodiment, preferablycomprises from about 1% to about 99%, more preferably from about 5% toabout 90%, and most preferably from about 10% to about 80%, by weight ofmolecular sieve. It is also preferred that the catalyst composition havea particle size of from about 20 microns to about 3,000 microns, morepreferably from about 30 microns to about 200 microns, most preferablyfrom about 50 microns to about 150 microns.

The catalyst can be subjected to a variety of treatments to achieve thedesired physical and chemical characteristics. Such treatments include,but are not necessarily limited to hydrothermal treatment, calcination,acid treatment, base treatment, milling, ball milling, grinding, spraydrying, and combinations thereof.

A preferred catalyst of this invention is a catalyst which contains acombination of SAPO-34, and SAPO-18 or ALPO-18 molecular sieve. In aparticularly preferred embodiment, the molecular sieve is a crystallineintergrowth of SAPO-34, and SAPO-18 or ALPO-18.

To convert oxygenate to olefin for use as olefin feed, conventionalreactor systems can be used, including fixed bed, fluid bed or movingbed systems. Preferred reactors of one embodiment are co-current riserreactors and short contact time, countercurrent free-fall reactors.Desirably, the reactor is one in which an oxygenate feedstock can becontacted with a molecular sieve catalyst at a weight hourly spacevelocity (WHSV) of at least about 1 hr⁻¹, preferably in the range offrom about 1 hr⁻¹ to 1000 hr⁻¹, more preferably in the range of fromabout 20 hr⁻¹ to about 1000 hr⁻¹, and most preferably in the range offrom about 20 hr⁻¹ to about 500 hr⁻¹. WHSV is defined herein as theweight of oxygenate, and hydrocarbon which may optionally be in thefeed, per hour per weight of the molecular sieve content of thecatalyst. Because the catalyst or the feedstock may contain othermaterials which act as inerts or diluents, the WHSV is calculated on theweight basis of the oxygenate feed, and any hydrocarbon which may bepresent, and the molecular sieve contained in the catalyst.

Preferably, the oxygenate feed is contacted with the catalyst when theoxygenate is in a vapor phase. Alternately, the process may be carriedout in a liquid or a mixed vapor/liquid phase. When the process iscarried out in a liquid phase or a mixed vapor/liquid phase, differentconversions and selectivities of feed-to-product may result dependingupon the catalyst and reaction conditions.

The oxygenate to olefins process can generally be carried out at a widerange of temperatures. An effective operating temperature range can befrom about 200° C. to about 700° C., preferably from about 300° C. toabout 600° C., more preferably from about 350° C. to about 550° C. Atthe lower end of the temperature range, the formation of the desiredolefin products may become markedly slow. At the upper end of thetemperature range, the process may not form an optimum amount ofproduct.

Olefins obtained by cracking hydrocarbon streams can also be used toform the olefin feed stream of this invention. It is preferable,however, that such olefins be combined with the olefin product of theoxygenate conversion reaction. This is because the olefins obtained by acracking process are generally high in non-reactive hydrocarboncomponents such as alkanes, are high in branchiness, and are high inother undesirable by-products such as sulfur, which can cause conversionproblems in the higher olefin reaction process. Therefore, additionalpurification of such a stream would be needed.

The olefin feed of this invention has a substantially reduced sulfur,nitrogen and/or chlorine content. According to one embodiment, theolefin feed also contains isoolefin at a concentration that does notsubstantially adversely affect the linear quality of dimerized oroligomerized product. Such product contains enough n-olefin andmono-branched mono-olefin to provide derivative products, particularlyesters, that are highly desirable for industrial end uses. Esterderivatives from the dimer and oligomer products of this invention willbe particularly suitable for use as plasticizers.

The sulfur content of the olefin feed of this invention should besufficiently low such that the activity of the catalyst used to form theolefin dimer or oligomer is not substantially inhibited. Preferably, thesulfur content in the olefin feed is not greater than about 1 ppm; morepreferably, not greater than about 0.5 ppm; and most preferably, notgreater than about 0.3 ppm by weight, calculated on an atomic basis.

The nitrogen content of the olefin feed of this invention should also besufficiently low such that the catalytic activity of the catalyst usedto form the olefin dimer or oligomer is not substantially inhibited.Preferably, the nitrogen content in the olefin feed is not greater thanabout 1 ppm; more preferably, not greater than about 0.5 ppm; and mostpreferably, not greater than about 0.3 ppm by weight, calculated on anatomic basis.

The chlorine content of the olefin feed of this invention should also besufficiently low such that the catalytic activity of the catalyst usedto form the olefin dimer or oligomer is not substantially inhibited.Preferably, the chlorine content in the olefin feed is not greater thanabout 0.5 ppm; more preferably, not greater than about 0.4 ppm; and mostpreferably, not greater than about 0.3 ppm by weight, calculated on anatomic basis.

It is also desirable, according to one embodiment, that the olefin feedstream of this invention be high in linear mono-olefin content so as tomaintain a sufficiently high conversion to higher olefin product havingfew branches. Preferably, the olefin feed stream comprises at leastabout 50 wt % linear monoolefin, more preferably at least about 60 wt %linear mono-olefin; and most preferably at least about 70 wt % linearmono-olefin. Preferably, the linear monoolefin is a C₂ to C₆ linearmono-olefin and has a C₆ and higher hydrocarbon content of not greaterthan about 20 wt %; more preferably, not greater than about 15 wt %; andmost preferably, not greater than about 10 wt %.

The olefin feed streams of this invention are contacted with the acidbased oligomerization catalyst in order to form desirable dimer and/oroligomer products. As used herein, dimerization and oligomerizationprocesses are considered interchangeable terms. The processes are alsoknown as higher olefins processes. Dimerization processes,oligomerization processes and higher olefins forming processes are allphrases that define the dimerization and/or oligomerization of lightolefins, particularly C₃-C₆ olefins, to form a dimer or oligomerproduct, the product also referred to as a higher olefin.

Conventional processes for removing oxygenated hydrocarbons from olefinstreams can be used to produce the olefin feed stream used in thisinvention. Such methods include water and alcohol washing, causticscrubbing, distillation, extractive distillation and fixed bedadsorption. Other desirable methods, such as those found in Kirk-OthmerEncyclopedia of Chemical Technology, 4th edition, Volume 9, John Wiley &Sons, 1996, pg. 894-899, the description of which is incorporated hereinby reference, can also be used. In addition, purification systems suchas that found in Kirk-Othmer Encyclopedia of Chemical Technology, 4thedition, Volume 20, John Wiley & Sons, 1996, pg. 249-271, thedescription of which is also incorporated herein by reference, can beused.

In one embodiment of the invention, olefin feed streams that areoligomerized according to this invention can be derived from a mainolefin source and treated to reduce oxygenated hydrocarbon content. Thetreated olefin stream can then be further separated to produce an olefinfeed of a particularly preferred range, e.g., C₂ to C₆ olefins.

In another embodiment of the invention, the olefin feed stream that isto be oligomerized is separated according to a particularly preferredrange, and the separated olefin feed is treated to reduce oxygenatedhydrocarbon. The order of separation and/or treatment to reduceoxygenated hydrocarbon content is not critical to the invention.

In another embodiment of the invention, acid based oligomerizationcatalyst life, particularly the life of zeolite oligomerizationcatalysts are increased by hydrating the olefin feed stream prior tocontacting the stream with the catalyst. This means that an amount ofwater effective in substantially increasing catalyst life is added.Preferably, water is added to the olefin feed stream such that thestream comprises from about 0.05 weight percent to about 2 weightpercent water. More preferably, water is added to the olefin feed streamsuch that the stream comprises from about 0.1 weight percent to about 1weight percent water. The desired proportion of water may beincorporated by saturating the feed at an appropriate temperature, e.g.,from about 25° C. to about 60° C., or by injecting water through a pump.

The oligomerization reaction process can take place at any temperatureeffective in oligomerizing olefin feed to oligomer product. In general,the reaction takes place at a temperature of from about 170° C. to about300° C., preferably from about 170° C. to about 260° C., and mostpreferably from about 180° C. to about 260° C.

Operating pressures are not critical to the oligomerization reaction. Ingeneral the reaction process is carried out at a pressure of from about5 MPa to about 10 MPa, preferably from about 6 MPa to about 8 MPa.

Flow of olefin feed through the reactor should be sufficient to carryout a reasonably high conversion, but not so low that there aresignificant amounts of undesirable side reactions. In general, thereaction is carried out at a weight hourly space velocity (WHSV) of fromabout 0.1 hr⁻¹ to about 20 hr⁻¹, preferably from about 1 hr⁻¹ to about10 hr⁻¹, and most preferably from about 1.5 hr⁻¹ to about 7.5 hr⁻¹.

Following the oligomerization reaction, the higher olefin product isoptionally recovered, and further converted to desirable derivativeproducts. These derivative products can be paraffin mixtures, obtainedby conventional hydrogenation processes and optional blending and/oradditional distillation. The paraffin mixtures can be used ashydrocarbon fluids and/or solvents in many applications, includingpaints and coatings, process fluids, metal cleaning, dry cleaning,cosmetics, pharmaceuticals, agrochemicals, degreasing, aerosolpropellants, adhesives, cleaners, inks, and other industrial andhousehold products.

Other higher olefins derivatives include thiols (often calledmercaptans) or sulfides, which are produced by reacting with a sulfurcompound. These are valuable starting materials for agriculturalchemicals, pharmaceuticals, cosmetic ingredients, antioxidants,fragrance components and polysulfides. They are also used aspolymerization regulators in rubber and plastics manufacture.

Examples of other derivatives include alkylated aromatics, usingconventional alkylation processes. The alkylated aromatics can befurther processed to their lubricant components or surfactantderivatives, or used as a hydrocarbon fluid as is.

A particularly desirable conversion process for higher olefins iscarbonylation in general or hydroformylation in particular. Theseprocesses lead to various derivatives, including esters, aldehydes, andalcohols. An overview of catalysts and reaction conditions ofhydroformylation processes is given for example by Beller et al. inJournal of Molecular Catalysis, A104 (1995), pages 17-85, the details ofwhich are incorporated herein by reference. See also UllmannsEncyclopedia of Industrial Chemistry, Vol. A5 (1986), pages 217 to 233;which is also incorporated herein by reference. Further description isfound in J.Falbe, Carbon Monoxide in Organic Synthesis, 1967; andJ.Falbe, New Synthesis with Carbon Monoxide, 1980.

Hydroformylation involves the contacting of the higher olefin product,carbon monoxide and hydrogen with the hydroformylation catalyst or itsprecursor. Hydroformylation catalysts are organometallic complexes ofthe metals of Group VIII of the periodic system, optionally used incombination as bior tri-metallic systems, and optionally with salts ofother metals as promoters, for example tin chloride. The catalyticorganometallic complexes are combinations of catalytic metals withvarious ligands. Preferred metals are cobalt, rhodium and palladium.

The organometallic catalyst can be introduced as the activeorganometallic complex, or the complexes can be made in situ fromcatalyst precursors and ligands introduced into a reaction zone.Suitable catalyst precursors include, for example, the respective metalhydrides, halides, nitrates, sulfates, oxides, sulfides and salts oforganic acids. Such acids include formates, acetates, or heavieralkylcarboxylic acids such as oleates or naphthenates. Other organicacids which can be used include alkylsulfonic or arylsulfonic acids.

Particularly desirable complexes for the hydroformylation of the higherolefins of this invention are the carbonyl compounds of the metalsmentioned, as well as those containing amines, triorganic derivatives ofphosphorous, arsenic or antimony, the respective oxides of thesederivatives, optionally functionalized to make them soluble in phasesthat under certain conditions can be separated from the organic reactorliquid.

Hydroformylation is desirably carried out at a temperature ranging fromabout 40° C. to about 220° C. Preferred is a temperature ranging fromabout 80° C. to about 200° C.; particularly about 90° C. to about 180°C.

Hydroformylation can be carried out at conventional hydroformylationpressure ranges. In general, hydroformylation is acceptable at apressure range of from about 1 to about 400 bar gauge. Medium and highpressure ranges are preferred ranges. In general, medium and highpressure ranges are considered to be in the range of about 40 to about400 bar gauge, more specifically in the range of about 50 to about 320bar gauge. Within these general pressure ranges CO-liganded catalystprocesses are particularly useful.

A high pressure range is generally considered in the range of about 175to about 400 bar gauge, more desirably about 190 to about 310 bar gauge.CO-liganged rhodium and cobalt catalyst processes are particularlyuseful in these high pressure ranges.

A medium pressure range is generally considered to be in the range ofabout 40 to about 175 bar gauge, more desirably about 50 to about 150bar gauge, and with certain catalysts it is desirable to be within arange of from about 60 to about 90 bar gauge. As an example, atriphenylphosphineoxide (TPPO)-liganded rhodium catalyst is particularlydesirable in the range of from about 50 to about 150 bar guage. Asanother example, a trialkylphosphine-liganded cobalt catalyst isparticularly desirable in the range of from about 60 to about 90 bargauge.

Hydroformylation can also be carried out in low pressure ranges. Ingeneral, the low pressure range will be in the range of from about 5 toabout 50 bar gauge, although a pressure range of from about 10 to about30 bar gauge is particularly useful. An example of a hydroformylationcatalyst which is particularly useful in the low pressure range isphosphine-liganded rhodium, more particularlytriphenylphosphine-liganded rhodium.

Other hydroformylation catalysts can be used within the pressure rangesdescribed. Such catalysts are described in Kirk-Othmer, 4^(th) Edition,Volume 17, “Oxo Process,” pages 902-919 and Ullman's Encyclopedia ofIndustrial Chemistry, 5^(th) Edition, Volume A18, “Oxo Synthesis,” pages321-327, the detailed descriptions of each being incorporated herein byreference.

It is desirable in some instances that hydroformylation be carried outat a carbon monoxide partial pressure not greater than about 50% of thetotal pressure. The proportions of carbon monoxide and hydrogen used inthe hydroformylation or oxo reactor at the foregoing pressures aredesirably maintained as follows: CO from about 1 to about 50 mol %,preferably from about 1 to about 35 mol %; and H₂ from about 1 to about98 mol %, preferably from about 10 to about 90 mol %.

The hydroformylation reaction is conducted in a batch mode according toone embodiment. Alternatively, the hydroformylation reaction can occuron a continuous basis. In a continuous mode, a residence time of up to 4hours is useful. If a plurality of reactors is employed, a residencetime as short as 1 minute is advantageous. Alternatively a residencetime is in the range of from about ½ to about 2 hours is useful.

Since the hydroformylation process of the invention takes place in theliquid phase and the reactants are gaseous compounds, a high contactsurface area between the gas and liquid phases is desirable to avoidmass transfer limitations. A high contact surface area between thecatalyst solution and the gas phase is obtainable in a variety of ways.For example and without limitation, contact surface area between thegaseous reactants and the liquid phase is obtained by stirring in abatch autoclave operation. In a continuous operation, the olefin feedstream of one embodiment is contacted with catalyst solution in, forexample, a continuous-flow stirred autoclave where the feed isintroduced and dispersed at the bottom of the vessel, preferably througha perforated inlet. Good contact between the catalyst and the gas feedis obtainable by dispersing a solution of the catalyst on a high surfacearea support. Such a technique is commonly referred to as supportedliquid phase catalysis. The catalyst is provided as part of a permeablegel.

The hydroformylation reaction is performed in a single reactor accordingto one embodiment. Examples of suitable reactors are found in U.S. Pat.Nos. 4,287,369 and 4,287,370 (Davy/UCC); U.S. Pat. No. 4,322,564(Mitsubishi); U.S. Pat. No. 4,479,012 and EP-A-114,611 (both BASF);EP-A-103,810 and EP-A-144,745 (both Hoechst/Ruhrchemie); and U.S. Pat.No. 5,763,678 (Exxon). Two or more reactor vessels or reactor schemesconfigured in parallel are used in another embodiment. In addition, aplug flow reactor design, optionally with partial liquid productbackmixing, provides an efficient use of reactor volume.

It is preferred, according to one embodiment, that the hydroformylationreaction be carried out in more than one reaction zone or vessel inseries. Suitable reactor configurations are disclosed, for example, byFowler et al in British Patent Specification No. 1,387,657, by Bunninget al in U.S. Pat. No. 4,593,127, by Miyazawa et al in U.S. Pat. No.5,105,018, by Unruh et al in U.S. Pat. No. 5,367,106. and by Beckers etal. in U.S. Pat. No. 5,763,678. Examples of individual hydroformylationreactors can of the standard types described by Denbigh and Turner inChemical Reactor Theory ISBN 0 521 07971 3, by Perry et al in ChemicalEngineers' Handbook ISBN 0-07-085547-1 or any more recent editions,e.g., a continuous stirred tank or a plug flow reactor with adequatecontact of the gas and the liquid flowing through the reactor.Advantageously these plug flow reactor designs or configurations includeways of partial backmixing of the reactor product liquid, as explained,for example, by Elliehausen et al in EP-A-3,985 and in DE 3,220,858.

Hydroformylated products have utility as intermediates in themanufacture of numerous commercially important chemicals, with theinvention further providing processes in which hydroformylation isfollowed by reactions producing such chemicals. The reaction productswill typically be a mixture of oxygenated compounds, since the higherolefin components used to make the products will generally include amixture of components. The higher olefin components are generally amixture of components, because the olefin feed stream that is used tomake the oligomeric olefin product will generally include a mixture ofolefins. However, the resulting hydroformylation product stream willgenerally be higher in linearity as a result of the high degree oflinearity of the oligomeric olefin and olefin compositions used upstreamof the hydroformylation reaction process.

Either in their pure form, or as part of the mixture in thehydroformylation product, aldehydes which are produced are optionallyaldolized, a term which includes the dehydration of the aldol condensateto form an unsaturated aldehyde. This aldolization can be performed withthe other aldehydes present in the stream, or with aldehydes that wereprepared separately and are added to the original aldehyde orhydroformylation product stream.

Aldol product is optionally hydrogenated to the corresponding alcoholmixture. If desired, the unsaturated aldehyde mixture from aldolizationcan be selectively hydrogenated to form the saturated aldehyde mixture.Any of the saturated aldehyde mixtures, either as made byhydroformylation or by selective hydrogenation of an aldol product, canhave special value when they are oxidized to their correspondingcarboxylic acids, or condensed with formaldehyde to polyols, or withammonia to imines which can be hydrogenated to amines. The acids andpolyols are valuable intermediates for esters, polyol esters, metalsalts, amides, and again for imines and amines.

Under circumstances where the olefin feed is ultimately derived from alow-value feedstock like natural gas, i.e., in cases where methane fromnatural gas is converted to methanol and the methanol to olefin, theproducts or product mixtures may have value as liquid transportablefuels, optionally after dehydration to the olefin, and if desiredhydrogenation to a paraffin or paraffinic mixture. Particularly valuablecompositions produce according to this invention are isononyl alcoholmixtures, made by hydroformylation and hydrogenation of octene mixtures.The invention also provides a valuable process for the manufacture ofisooctanoic acid, wherein the aldehyde from hydroformylation of aheptene mixture is separated from the hydroformylation product andsubsequently oxidized.

In another embodiment of the invention, the hydroformylation products ofthis invention are optionally hydrogenated to saturated alcohols.Formation of a saturated alcohol may be carried out, if desired, in twostages through a saturated aldehyde, or in a single stage to thesaturated alcohol, in which case it is desirable to form a saturatedaldehyde as an intermediate. The alcohols are then optionallyesterified, etherified, or formed into acetals or carbonates, which canbe used as plasticizers, surfactants or synthetic lubricants. The estersand ethers of the invention, or produced by the process of theinvention, are suitable for use as solvents, paint coalescers,plasticizers, adhesives, surfactants, viscosity index improvers,synthetic lubricants, flame retardants, lubricant components, anti-wearagents, hydraulic fluids, cetane improvers, drilling fluids,thermoplastic and textile processing aids, polymer, especially vinylchloride polymer, stabilizers, polymerizable monomers and fragrances.

Esterification is accomplished by reacting the alcohols of thisinvention with acids or anhydrides. The reaction process desirably takesadvantage of conventional processes. In these conventional processes, itis desirable to react the alcohols and acids at elevated temperaturesand pressures, and to drive the reaction toward completion by removingwater that is produced as a by-product.

Catalysts may be employed in the esterification reaction. Suitablecatalysts include, for example, titanium containing catalysts, e.g., atetraalkyl titanate, in particular tetra-iso-propyl or tetraoctyl orthotitanate, or sulphonic acid containing catalysts, e.g., p-toluenesulphonic acid or methylsulphonic acid. Also sulphuric acid catalyst maybe used. Alternatively, the esterification reaction may be preformedwithout the addition of a dedicated catalyst.

Catalyst present in the esterification reaction product may be removedby alkali treatment and water washing. Advantageously, the alcohol isused in slight, e.g., from 10 to 25%, molar excess relative to thenumber of acid groups in the acid.

The acid of the ester may be inorganic or organic; if the latter, acarboxylic acid is preferred. Aromatic acids or their anhydrides arepreferred for plasticizer manufacture, although aliphatic acids are alsoemployed. Additional examples of acids include, acetic, propionic,valeric, isovaleric, n-heptanoic, noctanoic, n-decanoic, neodecanoic,lauric, stearic, iso-stearic, oleic, erucic, succinic, phthalic(1,2-benzenedicarboxylic), isophthalic, terephthalic, adipic, fumaric,azelaic, 2-methylpentanoic, 2,4-dimethylheptanoic,2,4,6-trimethylnonanoic, sebacic, benzoic, trimellitic, pyromellitic,acrylic, methacrylic, tall oil, monobasic or dibasic cyclohexanoic,naphthenic and naphthalene-type acids, carbonic, nitric, sulphuric,phosphoric and phosphorous and their thioanalogous, acids and C₆ to C₁₃oxo and neo acids. The esters of the C₉ and especially the C₁₂ alcoholswith oxo and neo acids are especially useful as drilling fluids andpower transmission fluids. Phosphate esters are particularly desirableas flame retardants; while phosphite esters provide vinyl chloridepolymer stabilizers.

Esters with monobasic and dibasic acids are preferred for lubricants andlubricant components. Advantageously the resulting esters contain from15 to 40 carbon atoms. Adipates, azelates, and phthalates are especiallypreferred for lubricant manufacture. Esters with unsaturated carboxylicacids, e.g., with acrylic and methacrylic acid, provide polymerizablemonomers, suitable as sole or comonomer in thermoplastics manufacture,or in polymers used in or as adhesives, VI improvers, and coatingresins.

The esters of the invention may be used as a plasticizer for numerouspolymers. Examples include cellulose acetate; homo- and copolymers ofaromatic vinyl compounds e.g., styrene, or of vinyl esters withcarboxylic acids e.g., ethylene/vinyl acetate copolymers;halogen-containing polymers, especially vinyl chloride homo- andcopolymers, more especially those copolymers with vinyl esters ofcarboxylic acids, esters of unsaturated carboxylic acids e.g.,methacrylates, and/or olefins; nitrile rubbers; and post-chlorinatedvinyl chloride polymers. Poly(vinyl chloride) is of particular interest.

The proportion of plasticizer ester to polymer may vary within widelimits. A desirable range is from about 10 to about 200 parts by weightper 100 parts of polymer, preferably from about 20 to about 100 partsper 100 parts of polymer.

The esters of the invention may be used alone as plasticizer, or inadmixture with one another, or in admixture with other plasticizers, forexample, dibutyl, dipentyl, dihexyl, diheptyl, dioctyl, dinonyl,didecyl, diundecyl, didodecyl, ditridecyl phthalates, trimellitates oradipates, or butyl benzyl phthalate, or mixtures thereof. They may also,or instead, be used with a secondary plasticizer, e.g., a chlorinatedparaffin, Texanol isobutyrate, or a processing oil. If used inadmixture, it is the total proportion of plasticizer that isadvantageously within the ranges given above.

The plasticized polymeric compositions of the invention may be made upin numerous forms and have various end-uses. For example, they may be inthe form of a dryblend, a paste, or a plastisol, depending on the gradeof the resin employed. They may be used, for example, as coatings, indipping, spraying, injection or rotational molding, extrusion, or asself-supporting films and sheets, and may readily be foamed. End usesinclude flooring materials, wall coverings, molded products, upholsterymaterials, leather substitutes, electrical insulation, especially wireand cable, coated fabrics, toys, and automobile parts.

The invention also provides a composition comprising an ester of theinvention and a refrigerant, especially a fluorocarbon refrigerant, andmore especially HFC 32 (difluoromethane) or HFC 134a(1,1,1,2-tetrafluoroethane). More especially, the invention providessuch a composition also comprising at least one of a hydrolyticstability enhancer, e.g., a hindered phenol or an aromatic amine, anantioxidant, corrosion inhibitor, and a metal deactivator.

The following examples represent various embodiments of the invention,within the overall scope of the invention as described in the claims.

EXAMPLE 1

An olefin feed comprising 64 wt % butenes and 35 wt % butane, thebalance comprising propane and propylene was hydrated by passing theolefin feed at a temperature of about 39° C. through a thermostatedwater saturator prior to introducing the feed into an oligomeriztionreactor containing ZSM-22. The hydrated feed, which contained 600 ppm byweight water, was then contacted with the ZSM-22 in the reactor todetermine catalyst life at 92% conversion. The results are shown in theFIGURE.

EXAMPLE 2

Acetic acid was added to a portion of the hydrated olefin feed inExample 1 to obtain an acetic acid concentration of 300 ppm by weight.The olefin feed was then contacted with ZSM-22 catalyst in anoligomerization reactor to determine catalyst life at 92% conversion.The results are shown in the FIGURE.

EXAMPLE 3

Butanol and methyl ethyl ketone (MEK) was added to an olefin feedcomprising 64 wt % butenes and 35 wt % butane, the balance comprisingpropane and propylene to obtain an olefin feed stream containing 2 wt %butanol and 2 wt % MEK. The resulting olefin feed stream was thencontacted with ZSM-22 in an oligomerization reactor to determinecatalyst life at 92% conversion. The results are shown in the FIGURE.

The data of Examples 1-3, as shown in the FIGURE, demonstrate thatoxygenated hydrocarbon can adversely affect catalyst life of zeoliteoligomerization catalyst.

Having now fully described this invention, it will be appreciated bythose skilled in the art that the invention can be performed within awide range of parameters within what is claimed, without departing fromthe spirit and scope of the invention.

1. A method of making an olefin oligomer from an oxygenate, comprising:contacting the oxygenate with a molecular sieve catalyst to form anolefin stream containing at least one C₂ to C₁₂ olefin; removingoxygenated hydrocarbon from the olefin stream to obtain an olefin feedstream comprising less than 1,000 ppm by weight oxygenated hydrocarbon;and contacting the olefin feed stream with an acid based oligomerizationcatalyst an olefin oligomer, wherein the olefin feed stream is hydratedprior to contacting with the oligomerization catalyst.
 2. The method ofclaim 1, wherein the acid based oligomerization catalyst is a solidphosphoric acid catalyst.
 3. The method of claim 1, wherein the acidbased oligomerization catalyst is a zeolite oligomerization catalyst. 4.The method of claim 3, wherein the zeolite oligomerization catalyst isselected from group consisting of TON, MTT, MFI, MEL, MTW, EUO, ZSM-57,ferrierites, offretites, ZSM-4, ZSM-18, ZSM-23, Zeolite Beta,faujasites, zeolite L, mordenites, erionites and chabazites.
 5. Themethod of claim 4, wherein the zeolite oligomerization catalyst isZSM-22, ZSM-23 or ZSM-57.
 6. The method of claim 5, wherein the zeoliteoligomerization catalyst is ZSM-22 or ZSM-23.
 7. The method of claim 6,wherein the zeolite oligomerization catalyst is a selectivated catalyst.8. The method of claim 1, wherein the olefin feed contains less than 50wt % alkane.
 9. The method of claim 8, wherein the olefin feed containsat least 50 wt % olefin.
 10. The method of claim 1, wherein theoxygenate is methanol or dimethyl ether.
 11. The method of claim 1,wherein the hydrated olefin feed has a water content of 0.05 to 2 weightpercent.
 12. The method of claim 1, wherein the olefin feed streamcomprises greater than 5 ppm by weight oxygenated hydrocarbon.
 13. Themethod of claim 12, wherein the olefin feed contains less than 50 wt %alkane.
 14. The method of claim 13, wherein the olefin feed contains atleast 50 wt % olefin.
 15. A method of making an olefin oligomer from anoxygenate, comprising: a) contacting the oxygenate with a molecularsieve catalyst to form an olefin stream b) recovering an olefin streamcontaining at least one C₃ to C₆ olefin from the olefin stream of stepa), c) removing oxygenated hydrocarbon from the olefin stream of step b)to obtain an olefin feed stream comprising less than 1,000 ppm by weightoxygenated hydrocarbon; and d) contacting the olefin feed stream of stepc) with an acid based oligomerization catalyst to form an olefinoligomer, wherein the olefin feed stream is hydrated prior to contactingwit the oligomerization catalyst.
 16. The method of claim 15, whereinthe acid based oligomerization catalyst is a solid phosphoric acidcatalyst.
 17. The method of claim 15, wherein the acid basedoligomerization catalyst is a zeolite oligomerization catalyst.
 18. Themethod of claim 17, wherein the zeolite oligomerization catalyst isselected from the group consisting of TON, MTT, MFI, MEL, MTW, EUO,ZSM-57, ferrierites, offretites, ZSM-4, ZSM-18, ZSM-23, Zeolite Beta,faujasites. zeolite L, mordenites, erionites and chabazites.
 19. Themethod of claim 18, wherein the zeolite oligomerization catalyst isZSM-22, ZSM-23 or ZSM-57.
 20. The method of claim 19, wherein thezeolite oligomerization catalyst is ZSM-22 or ZSM-23.
 21. The method ofclaim 20, wherein the zeolite oligomerization catalyst is selectivatedcat.
 22. method of claim 15, wherein the oxygenate is dimethyl ether.23. The method of claim 15, wherein the hydrated olefin feed has a watercontent of 0.05 to 2 weight percent.
 24. The method of claim 15, whereinthe olefin feed stream comprises greater than 5 ppm by weight oxygenatedhydrocarbon.
 25. A method of making an olefin oligomer from anoxygenate, comprising: a) contacting the oxygenate with a molecularsieve catalyst to form an olefin stream; b) removing oxygenatedhydrocarbon from the olefin stream of step a); c) recovering an olefinstream containing at least one C₃ to C₆ olefin from the olefin stream ofstep b), following removal of the oxygenated hydrocarbon, to obtain anolefin feed stream, wherein the olefin feed stream contains less than1,000 ppm by weight oxygenated hydrocarbon; and d) contacting the olefinfeed with an acid based oligomerization catalyst to form an olefinoligomer, wherein the olefin feed stream is hydrated prior to contactingwith the oligmerization catalyst.
 26. The method claim 25, wherein theacid based oligomerization catalyst is a solid phosphoric acid catalyst.27. The method of claim 25, wherein the acid based oligomerizationcatalyst is a zeolite oligomerization catalyst.
 28. The method of claim27, wherein the zeolite oligomerization catalyst is selected from thegroup consisting of TON, MTT, MFI, MEL, MTW, EUO, ZSM-57, ferrierites,offretites, ZSM-4, ZSM-18, ZSM-23, Zeolite Beta, faujasites, zeolite L,mordenites. erionites and chabazites.
 29. The method of claim 28,wherein the zeolite oligomerization catalyst is ZSM-22, ZSM-23 orZSM-57.
 30. The method of claim 29, wherein the zeolite oligomerizationcatalyst is ZSM-22 or ZSM-23.
 31. The method of claim 30, wherein thezeolite oligomerization catalyst is a selectivated catalyst.
 32. Themethod of claim 25, wherein the olefin feed contains less than 50 wt %alkane.
 33. The method of claim 32, wherein the olefin feed contains atleast 50 wt % olefin.
 34. The method of claim 25, wherein the oxygenateis methanol or dimethyl ether.
 35. The method of claim 25, wherein thehydrated olefin feed has a water content of 0.05 to 2 weight percent.36. The method of claim 25, wherein the olefin feed stream comprisesgreater than 5 ppm by weight oxygenated hydrocarbon.